After the meeting, at about 10:30 a.m. (12:30 p.m. ET), Harmon shot Steven Singer, 48; a 43-year-old man who was in critical condition, and a 32-year-old woman, Thompson said.

The law firm of Osborn Maledon identified one of its attorneys, Mark Hummels, as one of the victims. He was involved in a client mediation when he was shot, the Phoenix firm said.

"We believe the two men were his targets," Thompson said. The woman, whose injury was not life-threatening, "just happened to be in the way when the shooting occurred."

Harmon then fled in a 2013 Kia Optima, Arizona license plate AVS-2052, he said. Harmon shot at a witness who was following him, Thompson said. "Anybody who contacts him needs to be aware that he is armed and dangerous," he said.

Two other people who were not shot were also taken to a hospital, one for "some other type of injury not related to gunfire," and the other "may have been related to stress," Thompson said.